Geology of Ethiopia and the Horn

These flashcards cover key geological terms and concepts related to the geology of Ethiopia and the Horn, including the geological time scale, plate tectonics, and various geological processes.

Geology

An earth science that deals with the evolution of the earth's processes and features.

Continental Drift Theory

The hypothesis that continents move relative to each other and were once joined as a single massive landmass called Pangaea.

Pangaea

A supercontinent that existed during the late Paleozoic and early Mesozoic eras, which broke apart to form the current continents.

Geophysics

The study of the Earth using measurements of its physical properties, including earthquake waves to understand its structure.

Geochemistry

The analysis of the chemical composition of rocks and minerals to uncover their origins.

Geochronology

The science of determining the age of rocks, sediments, and fossils.

Orogenesis

The process of mountain building through the folding and deformation of the Earth's crust.

Epeirogenesis

The vertical movement or tilting of the Earth's crust, often causing slow rising and sinking of landmasses.

Paleozoic Era

An era characterized by ancient life forms, particularly invertebrates, occurring approximately 600 to 225 million years ago.

Mesozoic Era

An era known for the predominance of reptiles, including dinosaurs, from about 225 to 70 million years ago.

Cenozoic Era

The most recent geological era, starting 70 million years ago, marked by the dominance of mammals and birds.

Absolute Dating

A method of determining the exact age of a rock or fossil in years, often using radiometric techniques.

Relative Dating

A technique that determines the sequence of geological events relative to one another without establishing actual dates.

Law of Superposition

A geological principle stating that in any undisturbed sequence of rocks, the oldest layers are at the bottom.

Carbon-14 Dating

A method used to determine the age of organic materials by measuring the decay of carbon-14 isotopes.

Potassium-Argon Dating

A method for dating rocks by measuring the ratio of radioactive potassium-40 to argon-40.

Seafloor Spreading

The process by which new oceanic crust forms at mid-ocean ridges as tectonic plates move apart.

Tectonic Plates

Large plates that make up the Earth's lithosphere, which move and interact at their boundaries.

Divergent Boundaries

Where tectonic plates move apart, often leading to the creation of new crust.

Convergent Boundaries

Where tectonic plates move towards each other, leading to subduction or continental collision.

Transform Boundaries

Where two tectonic plates slide past one another horizontally, often causing earthquakes.

Quaternary Period

The most recent period in the geological time scale, lasting from about 2 million years ago to present.

Great Rift Valley

A series of contiguous geographic trenches that runs from Lebanon to Mozambique, including the Ethiopian Rift.

Glacial Deposits

Sediments deposited by glaciers, often marked by features like moraines and outwash plains.

Lacustrine Deposits

Sediments accumulated in lake beds, often rich in organic material.

Fluvial Deposits

Sedimentary deposits formed by river action, typically found on riverbanks and floodplains.

Aeolian Deposits

Wind-driven deposits of materials, commonly occurring in arid or semi-arid regions.

Endogenic Processes

Geological processes that originate from within the Earth, leading to the formation of landforms.

Exogenic Processes

Processes that happen on the Earth's surface, modifying landforms through weathering, erosion, and deposition.

Denudation

The process of eroding or wearing away the Earth's surface, which exposes underlying rock layers.

Metamorphic Rocks

Rocks that have been altered by heat, pressure, or chemically active fluids, resulting in new mineral compositions and structures.

Basement Rocks

The oldest, deeply buried rocks that serve as the foundation for newer rock formations above them.

Sedimentary Rocks

Rocks formed by the accumulation of sediments, which can include clays, sands, and remains of ancient life forms.

Rift Valley

A linear-shaped lowland formed by the tectonic forces that pull apart the crust.